#define _CRT_SECURE_NO_WARNINGS 1
#include<iostream>

using namespace std;

int main()
{
	int a, b;
	cin >> a >> b;
	double res = 1;
	for (int i = 1, j = a; i <= b; i++, j--)
	{
		res *= j / i;
	}
	cout << res;
	return 0;
}